Comparison of three luminescent assays combined with a sandwich hybridization for the measurement of PCR-amplified human cytomegalovirus DNA

Identification of human tissue contaminated by cytomegalovirus is currently carried out by PCR amplification followed by measurement of the amplicons. Three luminescent detection systems undertaken after sandwich hybridization of the amplicons were compared. The sandwich hybridization takes place between a covalent linked capture probe, bound onto a plastic 96-well plate, and a biotinylated or digoxigenin-labeled detection probe. The three non-isotopic luminescent detection systems need either streptavidin-conjugated peroxydase or streptavidin-conjugated pyruvate kinase or antibodies conjugated with alkaline phosphatase. Detection of the enzymes was carried out by measurement of light emission in the presence of respectively, luminol for peroxidase or dioxethane for alkaline phosphatase. The kinase assay was carried out not only in the presence of its substrates, ADP and phospho-enol pyruvate, but also of luciferase, which converts the produced ATP into light. The method was found to be sensitive, with the luciferase bioluminescent assay with the production of a long lasting signal. Amplicons from eight clinical samples were detected by this combination of sandwich hybridization and the three luminescent assays. The results were comparable with nested PCR for the identification of positive samples. The same correlation was obtained with 45 clinical samples using only the pyruvate kinase detection system, The high performance of these assays is given by the specificity of the sandwich hybridization combined with the sensitivity of the luminescent detection systems. (C) 1997 Elsevier Science B.V.